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1. What is a Link in networking?

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Link is the connection between two devices in a network. The Link can be a hardware or a software type.

Hardware link types are cable, connectors etc.

Software link types are different types of protocols. We can have wired as well as wireless links.

E.g. wifi and bluetooth are wireless links. Sometimes both the hardware and software type links are required to establish connectivity between two devices.

2.     What are the different layers of the OSI reference model in networking?

In OSI model, there are seven layers. These layers are:

Physical Layer: This is the physical level at which the bits and bytes are transmitted through the network. It can be different kind of cables, optical fibers etc. It can also be different kinds of physical connectors.

Data Link Layer: This is the second layer in OSI model. It is used for transferring data between adjacent nodes in a network.

Network Layer: This layer is based on the type of network being used for transmission. There are different protocols at this level. One of the most popular protocols at this layer is Internet Protocol (IP). It is being used in the Internet.

Transport Layer: This layer provides services like connection oriented communication, reliable communication, congestion avoidance etc. In TCP/IP model, TCP protocol is at transport layer.

Session Layer: This layer provides stateless and stateful sessions to a user. It ensures that a user can continue the communication based on the previous messages sent.

Presentation Layer: This layer serves as a data translator for the network. This layer provides data to application layer for display to end user.

Application Layer: Different kinds of software applications constitute this layer. Compared to any other layers, this layer has more number of options.

3. What is Backbone network?

As the name suggests, the Backbone network is the central part of a system. It is the centralized infrastructure of the overall network that can distribute data to smaller networks and devices in the network.

Most of the data flows though the Backbone network. It can server as a main conduit of the data. We can add smaller networks or new channels to Backbone network.

We can also manage the Bandwidth options for different channels from Backbone network.

4. What is LAN?

LAN stands for Local Area Network. It is a network that involves devices and their connections in a small physical location. It can be as big as a room or a floor in a building.

E.g. In a specific floor of an organization, computers, printers, wifi routers, voip phone systems etc may be connected to same LAN.

5. What is a Node in networking?

Node is the smallest autonomous point in a network. Node can be an end point or it can be joint in the network.

It is a point connected to the overall network. Node can be a personal computer, printer, or any other connected device.

We need at least two nodes to create a network.

6. What is a Router?

As the name suggests, a Router is used for routing the traffic. We can connect two or more network segments to a router.

A Router can receive data from one network and send it to the other network segment.

Router is considered as an intelligent device in network that has information about how to route the data.

Router maintains routing table for deciding the routing of traffic.

Routing table contains information like- paths, bottlenecks, alternate paths, time taken to reach next node etc. This information is used for making routing decisions.

Router also has intelligence of how to resolve congestion in network. It can also help with sending data with priority to certain nodes.

Router operates at the Network layer of OSI model.

7. What is a point to point link?

A point to point link is the direction connection between two computers on a network.

The point to point connected computers do not need any other network device for connection. We just need the appropriate cable and Network Interface Card (NIC) for establishing a point to point connection between two devices.

8. What is Anonymous FTP?

FTP stands for File Transfer Protocol. Anonymous FTP provides file access to user without requiring any login. It is used for providing access to files on public servers.

In this case, a User does not need to identify itself with a username or password to access a file. Everyone can login as anonymous guest to access a file on Anonymous FTP.

9. What is subnet mask?

Subnet mask is used for identifying the extended network address and the host address.

The Subnet mask is generally of same format as the IP protocol address being used.

In IPV4, a subnet mask consists of 32 bits.

10. What is the maximum length up to which a UTP cable is effective?

We can use a single UTP cable to connect up to 90-100 meters. We can use a repeater or a switch to enhance the effectiveness of a UTP cable beyond this limit.

11.  What is Data encapsulation?

Data encapsulation is a core concept in the modern networking. With Data encapsulation we can break a large amount of data into smaller packets that can be easily managed.

These smaller packets can be transferred across the network. At the destination we can combine these packets to create the original data. We can use checksums etc to ensure the integrity of data.

Data encapsulation has enabled the transmission of large amount of data like- video files.

This ensures that there is no loss of information or quality during the transmission of a large amount of data over the network.

12. What is Network Topology?

Network Topology is the structure of a communication network. It is the physical or logical layout of the network that depicts the way nodes are connected to each other.

There are two basic categories of Network topologies:

Physical topology and Logical topology.

Physical topology depicts the cables, links and nodes of a physical network.

Logical topology can be of type LAN, WAN, Token Ring, Ethernet etc.

13. What is Virtual Private Network (VPN)?

As the name suggests, Virtual Private Network is a private network. But it is a private network created over a public network.

In VPN, users can send data to each other on the public network like- Internet as if the data is sent in a private network.

The most popular use of VPN is to allow employees to access their organization’s Intranet from outside the office.

VPN can be created by virtual point to point connections or virtual tunneling protocols. VPN also uses strong encryption to hide the contents of data being transmitted over the public network.

Establishing a strong authentication mechanism is very important in VPN. By authentication, we identify users and allow them to access the VPN.

14. What is NAT?

NAT refers to Network Address Translation. It is used in the Internet Protocol. It is a method of mapping an IP address space to another IP address space by modifying the network address information in the IP header of a packet.

Originally, NAT was developed as a shortcut to avoid the need of changing the address of every host machine when a network was moved. Over the time it became popular among organizations.

NAT is a popular technique to solve the problem of IPv4 address shortage.

Another popular technique along with NAT is IP masquerading. In IP masquerading, we can hide the entire IP address space (generally private addresses) behind a single IP address (generally public address). In this way, we send data to a public address that can internally forward it to specific private address.

IP masquerading and NAT are considered synonymous these days.

NAT can be of one to one type of it can be of one to many type.

15. What is the purpose of  Network Layer in OSI model?

Network layer is the layer 3 of OSI model. The main purpose of Network layer is to forward the packets across the network so that the packets can reach the destination node.

Network layer is connection less. A data packet travels from one point to another point without any acknowledgement being sent to the sender.  Internet Protocol (IP) is a popular protocol of Network layer.

One of the most important device in Network layer is Router. Network layer needs routers and routing mechanisms to transmit data through the network.

At Network layer, every host in the network is assigned a unique address. In Internet Protocol, the unique address is IP address.

16. How does network topology affect the networking decisions?

Network topology comes with many properties of the network. E.g. How many devices are connecting to network? What is the maximum length up to which network can exist? Is it a wireless network or a wired network?

Based on all these properties, we have to select the right devices, connectors, cables, links and equipment for the network.

For a Wi-Fi network, we may need different routers than the one used for wired networks. Wi-Fi network may not need cables to connect devices. Wired networks need cables of the type suitable for the type of the device and distance between the devices.

17. What is Routing Information Protocol (RIP)?

Routing Information Protocol (RIP) is a protocol for working with the routers and routing mechanisms. Some of the characteristics of RIP are as follows:

  • It is one of the oldest routing protocols based on distance vector.
  • It uses a simple hop count as a routing metric to decide the routing of packets.
  • In RIP, we use a limit on the maximum number of hops to prevent any cycle or loop formation.
  • The largest number of hops allowed in RIP is 15.
  • It is also the limiting factor in deciding the size of the network.
  • If there is a hop count of 16, it is considered as infinite distance. The route with hop count 16 is considered unreachable.
  • The latest version of RIP is RIPng (RIP next generation). It supports IPv6 networking.
  • There are two basic types of messages in RIP. Request message and Response message.

18. What are the different types of Timers in RIP protocol?

There are four types of timers in RIP protocol:

  • Update Timer: This timer controls the interval between two response messages. The default is 30 seconds.
  • Invalid Timer: This is the timer for keeping an entry in routing table. This is the maximum time an entry is kept in a routing table, without being updated. It is also known as Expiration timer. Default value is 180 seconds.
  • Flush Timer: This timer controls the time period between the time a route is marked unreachable and the time when the entry is deleted from routing table. Default value is 240 seconds. Router broadcasts about unreachable route to all of its neighbors for this period.
  • Holddown Timer: This is the timer for each route entry. Whenever hop count for a route increases we use this timer. During this time, we do not update the routing entry. So that routing entry gets stabilized. Default value is 180 seconds. It is not a timer in RFC. It is a Cisco specific implementation.

19. What are options for implementing security in a computer network?

With the growth of technology, there are many malicious users who try to connect to a network. In this regard we can use following options to make the computer network secure:

  • Anti-virus: We can install the latest anti-virus software to keep the network devices safe from any intrusion.
  • Firewall: Firewall is one of the most popular mechanisms of keeping network secure from any external threats. These threats can be a virus attack or denial of service attack.
  • Authentication: We can setup proper and strong authentication mechanisms to control the access to our network.
  • Secure Transmission: We can introduce secure transmission protocols to keep the data being transferred in network secure.

20. What is NIC?

NIC stands for Network Interface Controller. It is also referred as Network Interface Card or Network Adapter.

NIC is a hardware component to connect a device with the network.

NIC contains the physical circuit required to connect software one a device with the physical layer components like- cables or Wi-Fi waves etc.

NIC is considered as a physical layer as well as data link layer device. We can have low level addressing like MAC address on a NIC to uniquely identify a device on the network.

21. What is Wide Area Network (WAN)?

Wide Area Network is a network to handle a large geographic location. It is generally used with leased telecom lines.

With a WAN, an organization can carry out its operations over a wide area that can cover locations across the world.

It can even extend to different cities and countries.

A WAN can connect multiple LANs to connect smaller networks in different locations. WAN can also be used to connect LANs of different technologies.

Some of the popular types of WAN are: ATM, Cable Modem, Dial-up, DSL, ISDN, Frame Relay, Sonet etc.

22.    What is Physical Layer in OSI model?

Physical layer is considered as the Layer 1 of OSI model. It is the lowest layer. This layer consists of the electronic circuits that are used for transmitting data in the network.

It is one of the most complex layers of OSI model because there are a large number of technologies and devices present in this layer.

Some of the physical devices in this layer are: Modem, Ethernet Adapter, Ethernet Hub, Network Interface Controller etc.

The main tasks of Physical layer are:

  • Bit by bit delivery
  • Modulation
  • Line coding
  • Simplex
  • Multiplexing
  • Circuit switching
  • Carrier sense

23.    What are the layers in TCP/IP stack?

TCP/IP stack has following layers:

  • Link Layer: This layer is also known as Network layer. This layer defines the network topology of the underlying network. It includes the low level protocols and interfaces. This layer deals with the physical transmission of data from one device to another device. It works on the transmission of IP datagrams.
  • Internet Layer: This layer takes care of the exchange of the data across network boundaries. It provides a uniform view of the overall network. It hides the underlying complexities and topologies. It is the basic layer that makes communication possible on the Internet. The main protocol at this layer is Internet Protocol (IP). IP is responsible for transmitting data from source host to destination host. IP assigns IP addresses to hosts and it uses headers in the data packets to make decision about forwarding the packets to appropriate node/router so that packets can reach the destination host successfully. IP has two versions: IPv4 and IPv6.
  • Transport Layer: This layer is responsible for handling host to host communication. It can handle communication on same host as well as on different hosts. The popular protocols at this layer are TCP and UDP.

TCP is the Transmission Control Protocol. TCP provides connection establishment, flow control and reliable communication on this layer. UDP is User Datagram Protocol. UDP is a basic connection less protocol. It is not used for reliable communication.

  • Application Layer: In application layer, applications of different types can operate. The applications generate data and communicate with other applications with this data. Applications in TCP/IP can communicate with the applications on same host as well as different hosts. The broad categories of applications are built on client server architecture or peer to peer networking architecture. Some of the popular protocols at this layer are: HTTP, FTP, SMTP, SSH etc.

24.    What is a proxy server and how does it protect a network?

A Proxy server is a server (an application) located between a client and a server. The client requests the proxy server for any file, resource, web page, connection etc. The proxy server evaluates the request and forwards it to the actual server on the network. At this point, the actual server can handle the request.

As of today, there are a large number of proxy servers on the Internet to access world wide web. These proxy servers hide the underlying complexities of actual servers. Client can reach out to these proxy servers in a uniform way to get their request serviced.

Proxy server can be of these types: Open Proxy, Reverse Proxy, Forward Proxy.

Proxy server hides the complexities of network as well as it can perform sanity checks on the request. Proxy server can also perform content filtering, encryption, censorship etc.

All these features of proxy server protect the network from malicious users.

25.    What is Session Layer in OSI model?

Session layer is used for session management between users and application in OSI model. Session management involves tasks like opening session, closing session, session timeout etc.

Session layer is used in Remote Procedure Call (RPC) applications.

Session layer also takes care of authentication and authorization of users to create sessions.

In Java, session beans use the mechanism provided by Session layer.

26.    Why should we implement a Fault Tolerance System?

A Fault tolerant system can keep operating normally even in case of a failure in some of its components. With a distributed system the number of components increases.

This can lead to failure in component bringing the whole system down. To avoid this situation we build fault tolerant in the system.

A fault tolerant system increases the availability of a system. It is an essential requirement for life-critical system or highly available system.

E.g. For an Air Traffic Control system, we have to introduce fault tolerance. For a system like red light management, we have to introduce fault tolerance to make it highly available.

27. What is the meaning of 10Base-T?

10Base-T is a convention for describing a type of cable.

Here, 10 is the data transfer rate in Mbps. It means this cable supports 10Mbps data rate.

T refers to the twisted pair. This is the type of cable used in the network.

Base refers to the base band in stead of broad band.

28. What is a Private IP address?

A Private IP address is used on an internal network or the Intranet. The Private IP address can not be used outside the Intranet. Therefore, we can not use it for routing on the Internet.

The other term for Private IP address is Local IP address.

Internet Assigned Numbers Authority (IANA) has reserved following range of addresses to be used as private IP addresses:

  • to 10.255.255.255 : This range allows 16 million private IP addresses.
  • 172.16.0.0 to 172.31.255.255 : This range allows approximately 1 million private IP addresses.
  • 192.168.0.0 to 192.168.255.255 : This range allows 65000 private IP addresses.

The main purpose of Private IP addresses is to solve the internal communication between devices inside a home or an office.

29. What is Network Operating System (NOS)?

Network Operating System (NOS) refers to two different things.

  • NOS is a specialized operating system for Networking device like- router, firewall etc.
  • NOS is an operating system oriented to Networking, that allows file sharing, device access etc. This OS enables the devices on the network to connect with each other. Most of the latest operating systems like- Windows, Linux etc. already provide these Networking capabilities.

Therefore, NOS now refers mostly to the first definition. It is mainly used as an OS for Networking Device.

Some of the examples of NOS are:

JUNOS used in Juniper Networks devices, IPOS used in Ericsson routers, Dell Network Operating System (DNOS) used in Dell switches.

30.    What is Denial of Service (DoS) attack?

Denial of Service or DoS attack is an attack over the internet. It is used for making a system, website or machine unavailable for use by a malicious attacker. In general, DoS is performed by flooding the system with a large number of requests that are beyond the capacity of that system.

Due to this the regular users of the system do not get access to the system, or their requests are indefinitely delayed.

One of the type of DoS attack is Distributed Denial of Service attack (DDoS). In DDoS, the requests to flood the system originate from multiple sources.

Due to this it is difficult to identify the source attack. In DDoS, it is very difficult to stop the source of attack, because the attack is coming from multiple sources.

31. What is OSI model?

OSI model refers to the Open Systems Interconnection model. It is a model for defining the structure of a telecommunication or computing systems. Nowadays, it is heavily used for an overall Network system architecture.

This model is maintained by the International Organization for Standardization (ISO).

In OSI model, there are 7 abstract layers. Each layer serves a specific purpose in the overall Network.

The seven layers are:

  • Physical layer,
  • Data Link layer,
  • Networking layer,
  • Transport layer,
  • Session layer,
  • Presentation layer
  • Application layer.

32.    Why do we have to shield a cable or create a twisted pair?

In parallel cables, there are chances of Electro-Magnetic Interference (EMI). This EMI can cause cross talk or unnecessary noise in communication.

There are many options of reducing EMI. One of the popular options to prevent EMI is shielding a cable with a conducting material.

Another option is to twist a pair of cables. This helps in decreasing the noise level during communication.

33.    Why do we use address sharing in networking?

In Address sharing, multiple clients can share same IP address. It is generally done on a shared hosting environment.

There is a Network Address Translator (NAT) or Proxy server that takes care of converting the public IP address to the IP address of the specific server.

The main benefit of Address sharing is enhanced security.

The actual server is hidden from the public network because there is a NAT in the middle.

In home networks, router has the public IP address, but rest of the devices in the house have private IP addresses. Therefore, all these devices share the same public IP address for communication with the outside world. It helps in hiding the internal details of a home network.

34. What is a MAC address?

MAC address refers to Media Access Control address.

MAC address is assigned to an actual device. MAC address of a device’s network interface is the unique identifier assigned to this interface for any data link layer communication. MAC address are used in media access control protocol of OSI model.

In general, the manufacturer of device assigns a MAC address to the interface. It is a read only address. There is a coding convention to assign MAC address for a device. MAC address is made of 48 bit address space. Therefore we can have 2 to the power of 48 possibilities for MAC address. Compared to IPv4 addresses, we have a large supply of MAC addresses before running out.

35.    What are the layers corresponding to TCP/IP Application layer in OSI model?

In TCP/IP stack, Application layer is an overloaded layer.

It has three functions.

It serves the requirements for three layers of OSI model.

These three layers are: Session layer, Presentation layer and Application layer.

36.    How will you find the IP class of a given IP address?

We can find the IP class of a given IP address by referring to the first octet of 4 byte IP address. The rules for A, B, C class address are as follows:

  • If the first octet begins with 0 bit, then it is Class A IP network.
  • If the first octet begins with 10, then it is Class B IP network.
  • If the first octet begins with 110, then it is Class C IP network.

37.    Why do we use Open Shortest Path First (OSPF) protocol?

Open Shortest Path First (OSPF) protocol is used in routing tables. During the transmission of a packet, we have to identify the correct and efficient route for making the transmission possible.

In this case, we use OSPF to find the best possible path for data transmission.

It is a routing protocol for IP networks. With the help of this protocol, we can efficiently transmit data from one point to another point in a network.

38. What is a Firewall in networking?

Firewall is a network security system to protect the overall system by monitoring the incoming and outgoing traffic.

In a network we have a trusted internal network. The internal network is connected to a public network which is an untrusted network. To connect these two networks, we use a Firewall.

A Firewall is a computer software that monitor the traffic and protects the system from any attack by malicious users or viruses.

Some of the implementations of Firewall are: Packet filters, Application layer software, Proxy servers etc.

39. How does Star network topology work?

In Star network topology, we have a central hub. All the nodes in the system have to connect with the central hub.

In such  scenario, every node is connected to another node via the central hub.

It is one of the easiest network topology. At home, wifi router acts as the central hub to which all the home devices connect to.

The biggest disadvantage of Star topology is the single point of failure. In case, the central hub fails, the whole system comes down.

The biggest advantage of Star topology is the ease of adding or removing  device. The existing Star topology based system keeps working, as it is, even if one of the device other than the central hub fails.

40. What is a Gateway in networking?

In networking terms, a Gateway is a software or a device that is used for interfacing with another network on different protocol. Gateway is also known as Protocol Converter or Protocol translator.

In OSI model, Gateway operates at the Network layer. A Gateway is responsible for performing more tasks than a switch or router.

In a computer network, Gateway can perform the tasks of proxy server, DHCP server, firewall server etc .

There are many types of Gateways: Internet Gateway, Internet to orbit gateway, Cloud Gateway, IoT Gateway etc.

41. What are the disadvantages of using star topology?

Star topology in networking has following disadvantages:

  • Expensive: Star topology is considered an expensive option because it needs a large amount of cables to be setup. We need connection from each node to the central hub in Star topology based wired network. In wifi network, this is not a disadvantage.
  • Single Point of Failure: The biggest disadvantage of Star topology is the single point of failure. If central hub fails, the whole system can come down and become unavailable. Therefore, we use very high end systems for creating central hub in Star topology network.

42. What is SLIP in Networking?

SLIP stands for Serial Line Interface Protocol. It is a protocol for working with the Internet Protocol by using serial ports and modem connections. It is an old protocol used for legacy networking. The benefit of SLIP is very less overhead in communication.

SLIP uses just 8 bits for Serial Port configuration.

One the flip side, SLIP does not provide error detection. It is reliant on upper layers for any error handling. Therefore, SLIP is not suitable for an unstable dial up connection.

Nowadays, we use Point to Point Protocol (PPP) in place of SLIP.

43.    What are the different ranges of Private IPv4 addresses?

Different ranges of Private IPv4 addresses are as follows:

  • 10.0.0.0 to 10.255.255.255 : This is class A address range. It has a subnet mask of 255.0.0.0.
  • 172.16.0.0 to 172.31.255.255 : This is class B address range. It has a subnet mask of 255.240.0.0.
  • 192.168.0.0 to 192.168.255.255 : This is class C address range. It has a subnet mask of 255.255.0.0.

For IPv6 we have a different set of range for Private IP addresses.

44. What is Tracert?

Tracert is also known as Traceroute.

It is a computer program used for network diagnostics. We can use it to display the route as well as the transit delays of packets on Internet protocol stack.

Traceroute gives all the hops taken to reach a destination. Whereas PING gives only the final round trip time from start to destination point.

Tracert is available on Unix as well as Windows based systems. In Unix based systems it is available as trace route command line tool.

45.    What are the responsibilities of a Network Administrator?

Network Administrator is responsible for maintaining the computing infra structure of an organization with respect to networking capabilities.

Some of the main responsibilities of a Network Admin are as follows:

  • Network Setup: Network admin is responsible for initial network setup as well as adding new nodes to network for any new requirement.
  • Network Monitoring: Network admin takes care of monitoring the network for any issues. It ensures that network is always accessible and used in an appropriate manner.
  • Network Security: Network admin installs security mechanisms to keep the network secure from malicious users within the network or outside the network. We use firewall, anti-virus etc for this purpose.
  • Network Updates: Network admin updates the network nodes and software with the latest patches. This is important to keep the network secure against the latest viruses and attacks.
  • Network Filter: Network admin filters the traffic against spam attacks. It keeps internet usage and email usage efficient by blocking the unwanted and spam content on the network.

46.    What are the disadvantages of a peer to peer network?

Some of the major disadvantages of a peer to peer (P2P) network are as follows:

  • In a P2P network, every node can be accessed anytime. Due to this we have to keep every node always available.
  • In P2P network, we have to secure every node independently. We have to protect every node from malicious users all the time. It leads to a lot of overhead on each individual node.
  • Backup of every node in P2P network has to be performed in an independent manner.
  • There is no central hub responsible for managing access to data in a P2P network. This puts extra load of access control on each node.
  • For authentication, users of P2P network use distinct password for each distinct node in a P2P network.
  • If any one node is not fully secure in a P2P network, it can compromise the security of the entire network.
  • Load balancing is very difficult in a P2P network. Each node has to implement its own load balancing mechanism to handle heavy load situation.

47. What is Hybrid Network?

A Hybrid network provides the benefit of multiple types of network topologies. One of the most popular setup is to use Client Server and P2P topologies in a hybrid network.

In a Hybrid, two or more networks with different topologies are connected in such a way that it does not appear as a single type of topology.

E.g. A Tree Network (or a Star-Bus network) is a combination of Star and Bus topologies. In this there are multiple star topology networks that are connected through a bus.

There are other examples of Hybrid network like- Star ring network or a hybrid mesh network.

48.    What is Dynamic Host Configuration Protocol (DHCP)?

Dynamic Host Configuration Protocol or DHCP is a protocol to manage the network.

It is used on TCP/IP based networks. A DHCP server is the software/node that implements DHCP protocol.

  • DHCP server dynamically assigns IP addresses and configuration parameters to other nodes on the network.
  • DHCP supports a wide range of networks. It can be as small as a home network and as big as a university campus network.
  • DHCP can follow one of the three strategies for address allocation. Dynamic Allocation, Automatic Allocation, Manual Allocation.
  • DHCP is mainly used for IPv4 networks.

49.    What is the purpose of Address Resolution Protocol (ARP)?

Address Resolution Protocol or ARP is a protocol used for discovering the link layer address of a node. Link layer addresses are also known as MAC layer addresses or Physical addresses.

ARP is used as a communication protocol to enable communication between two devices at physical layer. To start the communication we need the physical address of a device. We use ARP to map the physical address with the IPv4 address. These mapping are cached in an ARP table on a device. This helps in easy and fast mapping of IP address to Physical address.

In IPv6, we use Neighbor Discovery Protocol (NDP) in place of ARP.

50. What is TCP/IP stack?

TCP/IP stands for Transmission Control Protocol/Internet Protocol. It is also known as Internet Protocol suite.

  • TCP/IP stack provides protocols for end to end data transmission over the Internet. It provides solution and rules for how the data should be packetized, addressed, routed, transmitted and received.
  • There are four layers in TCP/IP stack. These are: Link Layer, Internet Layer, Transport Layer, Application Layer.
  • TCP/IP stack is older than the OSI model of seven layers.
  • TCP/IP stack is also known as Department of Defense (DoD) model, because it was funded by DoD in USA.
  • Two most popular protocols of TCP/IP are TCP for Transport layer and IP for Internet layer.

51. How can we perform network management by using a router?

Every router has a console software application that can be used to configure the settings of router as well as the network it is connected to.

Some of the main network management settings in a router are as follows:

  • Access: We can specify in a router, which device has access to network and which device does not have access. We can block access of a device by specifying its MAC address.
  • Security: Router has provision for specifying the security mechanism WEP/WPA2 etc to be used for connecting to the network.
  • Distribution: Router can effectively distribute traffic across multiple routers. This is used for traffic management on a network.
  • Usage: We can also view the data usage of a device from router console. It can also be used for blocking certain devices when they exceed their quota of network usage.

52.    What is the protocol suitable for transferring files on a network?

We can use File Transfer Protocol (FTP) to transfer a file from one server to another server on a network. FTP is an open standard protocol with platform independent commands.

In its raw form, FTP is not considered a secure protocol. FTP is prone to many attacks.

For secure file transfer, we can use Secure File Transfer Protocol (SFTP).

We can also use Anonymous FTP for file transfer with anonymous access.

Some of the main commands in FTP are: ftp, cd, lcd, get, put, mget, mput etc.

53.    What is a default gateway in a network?

As the name suggests, a gateway is a node on a network that provides access to that network from the outside world.

The main purpose of default gateway is to be the default node for any data transmission when there is no specific node to which data should be forwarded.

Default gateway is a node on the Internet Protocol suite based network. Whenever, router can not find a specific node on the network corresponding to a route, it just forwards the data to Default gateway.

In configuration settings, default gateway is mentioned as default route.

In home or office networks, the router that connects the internal devices to the external internet is considered as Default gateway.

54.    What are the best practices of selecting a strong password for network security?

Some of the best practices of selecting a strong password for network security are as follows:

  • A strong password should contains letters, numbers and special characters.
  • A strong password should have uppercase as well as lowercase letters.
  • A strong password should have more than 8 characters.
  • A strong password should not match dictionary words.
  • A strong password should not be based on personal data like- birthdate, child name, favorite movie, book etc.

55.    What are the advantages and disadvantages of using UTP cables?

UTP cable is also known as Unshielded Twisted Pair (UTP) cable. Some of the advantages of UTP cables are as follows:

  • Noise: Electrical noise going into or coming from the UTP cable can be prevented.
  • Crosstalk: In a UTP cable, Crosstalk is minimized.
  • Cost effective: UTP cables are one of the cheapest options for networking.
  • Ease of use: UTP cables are considered very easy to install and use on a network.

Some of the disadvantages of UTP cables are as follows:

  • Deformation: A UTP cable can have distorted communication due to electromagnetic interference. Therefore, we have to create the twisted cable with proper standards.
  • Delay: Some of the UTP cables can have delay during transmission. Since there are two cables in a UTP, there can be delays between two cables.

56. What is the use of Netstat?

Netstat is also known as Network Statistics. It is a command line program. Netstat is used on TCP/IP protocol.

We can use Netstat to view the network connections of TCP protocol.

Netstat can also be used to find problems in network. It is a very good diagnostic tool on the Internet.

Netstat can provides network statistics for following items on a network:

  • Protocol: Netstat can provide the name of the protocol being used. It can be TCP or UDP.
  • Local Address: Netstat can print the IP address of the local computer and the port number being used.
  • Foreign Address: Netstat can be used to find the IP address and port number of the remote computer to which a socket is connected.
  • T State: Netstat can indicate the current state of a TCP connection.

Some of the states are: CLOSE_WAIT, CLOSED, ESTABLISHED, FIN_WAIT_1, FIN_WAIT_2, LAST_ACK, LISTEN, SYN_RECEIVED, SYN_SEND, and TIME_WAIT.

57.    How many total number of network IDs available on a Class C network?

On Class C network we can have network addressees from 192.168.0.0 to 192.168.255.255

If the first octet begins with 110, then it is Class C IP network.

The class C address range has a subnet mask of 255.255.0.0.

The total number of IDs available on Class C network are 65000.

58.    What is the impact of using cables for a distance longer than the prescribed length?

In networking, there is a problem of signal attenuation. In plain words, it means signal loss. If we use cables for a longer distance than the prescribed length, there will be chances of signal attenuation.This will lead to low quality transmission.

It can even cause data loss.

Imagine, you are sending an important message. But due to signal loss only half of the message reaches the recipient.

Therefore, it is better to use cables for prescribed length in a network.

59.    What are the most common network issues that are result of a software problem?

Some of the most common network issues that are result of a software problem are as follows:

  • Application Conflict
  • Configuration Error
  • Protocol Incompatibility
  • User Authentication Issues
  • Security Loopholes in Software
  • Client Server Issues due to heavy load

60.    What is Internet Control Message Protocol (ICMP)?

Internet Control Message Protocol or ICMP is a protocol that supports Internet Protocol in TCP/IP stack. It is mainly used for routers to send the error messages and operational messages.

ICMP messages are encapsulated in a IPv4 packet. There is a header and payload by ICMP.

In ICMP header we can specify ICMP Type and Subtype.

Some of the popular ICMP type are: Destination unreachable, Source quench, Redirect message, Echo request, Time exceeded, Router announcement, Timestamp etc.

One of the popular utility program, Ping used ICMP messages to work.

61. What is Ping utility?

Ping is a software program. It is used for network administration.

Ping is used to test whether a host is reachable on the Internet protocol.

Ping internally used ICMP protocol for its operation.

Ping provides command-line options like- specifying the size of the payload, limits for the number of network hops, count of tests, interval between the requests etc.

For testing IPv6 networks, we can use ping6 software utility.

62.    What is Peer to Peer (P2P) network?

A P2P network is based on distributed computing architecture. In a P2P network there is no main server. Therefore it is different from client server architecture.

In a P2P network, all the peers or nodes are equally privileged.

Every peer makes some part of their resources available to the rest of network participants.

One of the most popular examples of P2P network base application was Napster. This was a file sharing platform based on P2P architecture.

63. What is Domain Name System (DNS)?

Domain Name System is also known as DNS.

  • DNS is a hierarchical system for naming domains.
  • DNS is a centralized platform to map and find names of computers, servers, services, nodes etc.
  • DNS maps a human readable domain name to an IP address. An IP address is a 32 bit number.
  • The authority to assign a domain name to an IP address lies with separate organizations.
  • We use a DNS server to find the IP address associated with a domain name. Once IP address is found, we can use it for data communication on the Internet layer.
  • DNS server implements algorithm and mechanisms to avoid circular dependencies.
  • DNS server also uses caching mechanism to resolve Domain names efficiently.

64.    What are the advantages of optical fiber over the copper wire?

Some of the main advantages of optical fiber over the copper wire are as follows:

  • Broad bandwidth: A single optical fiber can carry more than 3,000,000 full-duplex voice calls. It can even transmit 90,000 TV channels.
  • Immunity to electromagnetic interference: IN an Optical fiber, light transmission is unaffected by other electromagnetic radiation. Since optical fiber is electrically non-conductive, it does not pick up electromagnetic signals. Information traveling inside the optical fiber has not impact of electromagnetic interference.
  • Low attenuation: Signal Attenuation loss in Optical fiber is as low as 0.2 dB/km. Therefore we can transmit data over long distances without the need for repeaters.
  • Electrical insulator: Optical fibers are poor conductors of electricity. It prevents the problems of ground loops and conduction of lightning. Optical fibers can also be strung on poles along with high voltage power cables.
  • Material cost and theft prevention: There is a large amount of Copper in a Conventional cable system. Due to high price of copper, these cables are a prime target of theft.
  • Security of information passed down the cable: It is very easy to tap into a Copper wire.

65.    What is the difference between a hub and a switch?

A hub acts as a multiport repeater. However, as more and more devices connect to it, it would not be able to efficiently manage the volume of traffic that passes through it.

A switch provides a better alternative that can improve the performance especially when high traffic volume is expected across all ports.

A switch is more intelligent than an Ethernet hub, which simply retransmits packets out of every port of the hub except the port on which the packet was received, unable to distinguish different recipients, and achieving an overall lower network efficiency.

A switch does essentially what a hub does, but more efficiently. By paying attention to the traffic that comes across it, it can “learn” where particular addresses are. Initially, a switch knows nothing and simply sends on incoming messages to all ports:

Even accepting that first message, however, the switch has learned something – it knows on which connection the sender of the message is located. Thus, when machine “A” responds to the message, the switches only need to send that message out to the one connection:

66.    What protocols fall under the Application layer of the TCP/IP stack?

The following are the protocols under TCP/IP Application layer

  • BGP Border Gateway Protocol
  • DHCP Dynamic Host Configuration Protocol
  • DNS Domain Name System
  • FTP File Transfer Protocol
  • HTTP Hypertext Transfer Protocol
  • IMAP Internet Message Access Protocol
  • LDAP Lightweight Directory Access Protocol
  • SIP Session Initiation Protocol
  • SMTP Simple Mail Transfer Protocol
  • SNMP Simple Network Management Protocol
  • SSH Secure Shell
  • Telnet TLS/SSL Secure Socket Layer

67.    How can you connect two computers for file sharing without using a hub or router?

We can simply use a cable to connect two computers. By using this we establish the connection to share file between two computers.

68. What is Ipconfig tool?

Ipconfig stands for Internet Protocol Configuration. It is a utility in Microsoft environment for displaying all the current TCP/IP configuration values on a computer. It displays IP as well as physical addresses of all the interfaces on the computer. Now MAC OS X also provides ipconfig tool on apple computers.

69.    What is the difference between a straight through cable and crossover cable?

We use a straight through cable to connect a computer to a switch, router or a hub.  We use crossover cable for connecting two devices of same type with each other.

70. What is Client server model?

In a client server model, there are multiple computers acting as clients. But only one computer acting as a server.

It is a centralized system in which clients make request to server.

It is used in printers, filesystems etc. resources.

In general, client server is implemented as a passive server. It means server waits for requests from client. Once server receives a request, it processes the request and sends response back to client.

71. When we take out a Network Interface Card (NIC) from a device and put it in another device, does the MAC address also gets transferred?

MAC address is hard coded into the Network Interface Card (NIC) circuit. It is not a property of device. Due to this, when we move NIC from one device to another device, the MAC address also gets transferred.

72. What is clustering support in Networking?

In Networking we can create a cluster by connecting multiple servers. This is done to introduce fault tolerance in the network system. This capability of adding multiple servers in a network operating system is known as clustering support.

We build cluster of servers so that even if one server fails, the other servers continue to work.

73.    What is the best place to deploy an Anti-virus software in a network?

In general, we deploy Anti-virus software on all the nodes in a network. It is done to introduce security and safety in the system.

There are individual nodes or computers on which we can replace hard disks or flash drives. These hard disks or flash drives may have virus programs. Due to this the whole network can get infected. It is better to install anti virus on each computer so that we can keep the system safe from virus and malicious software.

74. What is Ethernet?

Ethernet is a networking technology used in Local Area Network (LAN). It was commercially used in 1980. In its original version Ethernet used Coaxial cable for data transmission.

It is one of the most popular technology for creating Network in home or office.

As of now Ethernet can handle very high bandwidth traffic. It can also connect different kinds of physical media.

Although initial version of Ethernet was prone to collision, the latest version is practically free from collision of packets.

We can use repeaters and hubs to solve the problem of signal attenuation on the Ethernet.

The most popular version of Ethernet implementation is based on the IEEE standard 802.3.

75.    What are the disadvantages of using Ring topology in network?

Some of the disadvantages of using Ring topology in network are as follows:

  • In a Ring structure, if one node fails, it can bring down the entire network. We can use a switch to solve this issue.
  • If we move or relocate a node in Ring structure, it can have side-effects on the overall network.
  • In a Ring network, communication delay increases with the increase in the distance between nodes.
  • All the devices share the bandwidth in Ring topology. This leads to lower bandwidth per node.
  • Ring topology is difficult to configure than other types of topologies like- Star, Bus etc.

76. How is CSMA/CD different from CSMA/CA?

CSMA/CD stands for Carrier Sense Multiple Access / Collision Detect. CSMA/CA stands for Carrier Sense Multiple Access / Collision Avoidance.

CSMA is a media access protocol. CSMA/CD and CSMA/CA are two versions of this protocol. In CSMA/CD, the connection is terminated when a collision is detected. Due to this the time period between retry attempt can be reduced.

In CSMA/CA, the collision is avoided to improve the performance of transmission. If transmission is busy, CSMA tries the transmission after a random time interval.

77.    What is Simple Mail Transfer Protocol (SMTP)?

Simple Mail Transfer Protocol or SMTP is a protocol used for electronic mail (email) transmission.

SMTP is based on client server model. SMTP server listens for mail requests on port 25. Mail clients can submit mail requests to SMTP server.

SMTP is a connection oriented protocol.

SMTP uses a TCP connection for data transmission.

SMTP is mainly used for email delivery.

SMTP is different from Post Office Protocol (POP) that is used for email retrieval.

SMTP supports client authentication for accessing SMTP server.

78. What is multicast routing?

Multicast routing is a form of broadcast. In Multicast routing message is sent to a group of nodes on a network.

In broadcast, the message is send to all the nodes on a network.

Multicast routing is also known as group communication on a network.

One of the best example of Multicast routing is on streaming media application like Netflix.

Another good use of Multicast is in a video conference call.

79.    Why do we need to implement Encryption on a network?

On a network, data is transmitted from one node to another node. At times, some malicious user can connect to the network and start listening this data.

If our data is not encrypted, then the malicious user can read the data. To avoid this issue, we encrypt the data with a strong encryption algorithm, so that malicious user can not decrypt the data.

This saves our data from getting into wrong hands.

On a public network like the Internet, it is very important to encrypt data because our data passes through multiple nodes. If any one of the node is compromised then our data can be compromised.

80.    What is the use of authentication on network?

We use Authentication to verify the identity of a user on network. Once a user is allowed access to the network, the user can get any data or communication from the network.

Therefore, it is essential to check the credentials of a user before letting him connect to the network.

The most popular form of authentication is username password.

Nowadays we use Multi Factor Authentication (MFA) to authenticate the user with information other than username and password.

81. What is Tunnel protocol of data exchange?

Tunneling protocol is a mechanism by which a user can get access to a network service that is not directly provided to the user.

E.g. Using IPv6 over IPv4.

In general, we use repackaging of data for tunneling service.

Another use of Tunneling protocol is to assign a network address to  remote user who is not on physical location of the corporate network.

One of the popular uses of tunneling is on Secure Shell Tunneling.

82. What is IP Masquerading?

IP masquerading is a technique used on networks to hide the entire IP address space. It is generally used for hiding private IP addresses on a network. These private IP addresses are hidden behind a public IP address.

One of the most popular implementation of IP Masquerading on IPv4 network is by using Network Address Translation (NAT) method.

In NAT, we map one network address space to another address space. The change is done in the IP header of packets while they are in transit.

83.    What are the advantages of Mesh topology based network?

Some of the advantages of Mesh topology based network are as follows:

In a Mesh network, each connection is responsible for carrying its own data load. Therefore bandwidth for individual connection can be increased or decreased based on the load.

Mesh network is fault tolerant and it is considered more robust in comparison with other topologies.

It is easier to find and fix fault on a Mesh network.

Mesh network is considered more secure than other topologies.

There is no single point of failure in a Mesh network.

84. What is Network Virtualization?

Network virtualization is a process of using hardware and software resourced to create a network as a single entity that can be managed by a software. Network virtualization is similar to platform virtualization or resource virtualization.

Network virtualization is also considered as external virtualization. We can combine many parts of a different networks to create a virtual unit called virtual network. This network provides same functionality as an actual physical network.

Network virtualization is also used by software engineers for testing. We can use Network virtualization to test the software under development. Software test uses a virtual network to create the environment in which actual software will be deployed and used.

85.    What are the products from Amazon Web Services for Networking?

Amazon Web Services (AWS) provides many services for networking solutions. Some of these are as follows:

  • Amazon VPC:  Virtual Private Cloud (VPC) is used for isolating the cloud resources by creating our own private virtual network.
  • AWS Direct Connect: This is used to create dedicated and direct connections between different services in AWS. We can use it to create the dedicated network connection between our network and our Amazon VPC.
  • Elastic Load Balancing: It is a load balancing service for network based services. ELB can automatically distribute application traffic across multiple Amazon EC2 instances in the AWS cloud.
  • Amazon Route 53: It is a Domain Name Service (DNS) in AWS. Route 53 is a highly available and scalable cloud DNS service for connecting user requests with our AWS resources.

86.    What are the main benefits of Amazon Virtual Private Cloud (VPC)?

We can get following benefits by using Virtual Private Cloud (VPC) in an AWS account:

We can assign Static IPv4 addresses to our instances in VPC. These static IP addresses will persist even after restarting an instance.

We can use IPv6 addresses with our instances in VPC.

VPC also allows us to run our instances on single tenant hardware.

We can define Access Control List (ACL) to add another layer of security to our instances in VPC.

VPC also allows for changing the security group membership of instances while they are running.

87.    What are the different types of load balancing options provided by Amazon Elastic Load Balancing (ELB)?

Amazon Elastic Load Balancing (ELB) provides two types of load balancers:

  • Classic Load Balancer: This Load Balancer uses application or network load information to route traffic. It is a simple approach of load balancing to divide load among multiple EC2 instances.
  • Application Load Balancer: This Load Balancer uses advanced application level information to route the traffic among multiple EC2 instances. It can even use content of the request to make routing decisions.

88.    What can be done to fix signal attenuation problems?

Signal Attenuation refers to the decrease in the strength of signal in a network. It is quite common in a Wifi network. In wired networks, signal attenuates with distance.

Some of the main reasons of Signal Attenuation are:

  • Noise: The noise in surroundings can also cause signal to become weaker.
  • Physical Surroundings: There are physical factors like- wall, water body, underground location etc can cause signal to be weaker.
  • Distance: This is one of the most common cause of signal attenuation. Every technology has a limitation of the distance unto which it can work. When we reach the limit of that distance, signal becomes weaker.

To fix signal attenuation we can use following:

  • Repeater: We can use a repeater or hub to make the signal stronger.
  • Distance: We can try reducing the distance between a device and signal transmitter.
  • Installation: We can check cables installation to see if they are tied properly. This can also reduce the signal attenuation due to loose connections.

89.    What are the benefits of Dynamic Host Configuration Protocol in network administration?

Dynamic Host Configuration Protocol (DHCP) is an important protocol used for network administration in the Internet.

Some of the benefits offered by DHCP are as follows:

  • Reliable Configuration: We can minimize the occurrence of configuration errors by using DHCP. It also helps in preventing duplicate IP address assignment to multiple machines. A lot of manual errors can also be avoided by using DHCP.
  • Reduced Manual Work: With DHCP we do not need to do a lot of manual work in network administration.
  • Central TCP/IP: TCP/IP configuration is automated and centralized in DHCP.
  • Client Friendly: Clients can themselves assign a range of IP addresses to their TCP/IP configuration.
  • Router Efficiency: Many routers support DHCP. This  eliminates the need of a dedicated DHCP server.

Instead of having to visit each client computer to configure a static IP address, the network administrator can apply dynamic host configuration protocol to create a pool of IP addresses known as scopes that can be dynamically assigned to clients.

90. What is Profile in networking?

A Profile is the combination of settings that we can create for a user or a role. We can setup the configuration on network in a way specific to a user’s use case. This configuration setup is called Profile.  We can create a Profile for a role and assign that role to multiple users.

91. What is Sneakernet?

Sneakernet is an informal term. Sneakernet refers to the transfer of data by using non-conventional methods like- transmitting tapes, floppy drives or flash drives.  It refers to the wearing of Sneakers (shoes) to transmit data over a network. Some people call it train nets or pigeon nets also.

AWS has a service called AWS Snowball. This is an example of Sneakernet. In Snowball, user takes backup of data on an AWS device and then Amazon transports this device from user’s location to AWS location. This is a very efficient and less expensive service to transmit a large amount of data.

92.    What is the significance of IEEE in networking?

IEEE stands for the Institute of Electrical and Electronics Engineers. It is a professional organization of engineers. IEEE also creates and manages standards for Electrical and Electronics devices.

In networking most of the devices like NIC, Cables, Routers etc are either electronics or electrical devices. IEEE provides standards for these devices. This ensures that there is uniformity and compatibility between the devices in a network.

93.    What are the important protocols Internet Layer in TCP/IP stack?

The important protocols of Internet Layer in TCP/IP stack are as follows:

  • Internet Control Message Protocol (ICMP): This protocol is not used for actual data transmission in IP. It is mainly used for sending control messages and error messaged for diagnostic purposes.
  • Internet Group Management Protocol (IGMP): This protocol provides the multicast specification in IP. It is used in one to many network applications. E.g. Online video streaming, online games etc.
  • Internel Protocol (IP): IPv4 or IPv6 are the actual protocols at this level. This protocol is used for delivering packets from one location to another location. It is a connectionless protocol. IP is based on the best effort delivery model. It does not guarantee the delivery of data.
  • Internet Protocol Security (IPSec): This protocol provides the features like authentication and encryption in Internet Layer. IPSec uses cryptography based technologies to encrypt the data being transmitted through the Internet.

94. What are Rights in networking?

Right in a network is the permission to perform a specific task. In a network, we can first define all the actions. Then we create permission or rights for these actions.

These rights can be assigned to a user or a group on need basis. This helps in implementing security and authorization in a network.

95. What is the purpose of VLAN?

VLAN is also known as Virtual LAN. By using VLANs, network administrators can group together multiple hosts virtually. We need not carve a physical sub-network out of the existing network. We can just create a VLAN for this purpose. The membership to a VLAN can be configured by using software applications.

The main uses of creating a VLAN are: Scalability, Security and Network Management.

We can do network segmentation by creating VLANs. This simplifies the overall work of Network Management.

96.    What are the main features of IPv6?

The main features of IPv6 are as follows:

  • IPv6 offers more IP addresses than IPv4.
  • IPv6 implements stateless address auto-configuration.
  • IPv6 provides network renumbering.
  • In IPv6 packet fragmentation is done at the end points. This simplifies the processing of packets.
  • IPv6 provides enhanced security features.
  • IPv6 supports Jumbograms. These are the payloads with much higher capacity than that of IPv4 packets.

97.    What is the purpose of RSA algorithm?

RSA stands for Rivest, Shamir and Adleman. These are the three inventors of RSA algorithm, We use RSA algorithm for securing data. It is a public key crypto algorithm. In RSA, encryption key is public. It means everyone knows about the key used for encryption.

The public key is transferred along with encrypted data over the network. But decryption key is different from encryption key. And decryption key is private.

To implement RSA, we first create and publish a public key. This key is based on the multiplication of two very large prime numbers. These prime numbers are kept as secret. These numbers create the private key. Now anyone with public key can encrypt a message and send it to us. But only the generator of public key knows the private key. And we can decrypt the data by using private key.

RSA is one of the most popular encryption algorithms of today.

98. What is Mesh topology?

In Mesh topology, nodes are connected to each other directly and dynamically. There is no hierarchy in Mesh topology. A Node can connect to as many other nodes possible.

In general, Mesh networks are self configured and self governed. This is very useful in reducing the installation overhead.

In case of a node failure, self configuration property helps the other nodes to dynamically connect with other nodes and distribute the workload. This leads to increase in fault tolerance and decrease in maintenance overheads. E.g. Google Home, Google Wifi etc. support mesh topology.

99.    What is the maximum length up to which a segment of a 100Base-FX network can be extended?

The 100Base-FX network is a fast Ethernet over fiber optics. One segment of this network can be extended up to 412 meters for half duplex connections. We can extend it to 2000 meters for full duplex connections over multi-mode optical fiber.

100. What are the different ways to exchange data?

Different ways to exchange data in a network are as follows:

  • Simplex: In Simplex communication, data is sent in only one direction.
  • Half-duplex: In Half duplex communication, data can be sent in both the directions. But it uses same channel. Due to this communication takes place in only one direction at a time.
  • Full-duplex: In Full duplex communication, data can be sent in both the directions at the same time. We need two Simplex for creating Full-duplex.